The oligomerization of olefins is known in the art, subh oligomerization processes being effected by treating olefinic hydrocarbons with certain catalysts to obtain various oligomers which will find a useful function in the chemical art. One type of catalyst which may be employed for this particular type of reaction comprises a supported metal compound. For example, U.S. Pat. No. 3,562,351 discloses a method for dimerizing olefins utilizing a supported catalyst which has been prepared by impregnating a suitable support with a salt solution of a Group VIII metal followed by a heat treatment in an inert atmosphere at a temperature less than that which is required to form a metal oxide but which will form a complex on the surface of the solid support. Following this, the catalyst is activated by treatment with an organometallic compound. U.S. Pat. No. 3,483,269 describes a catalyst useful for oligomerizing lower olefins which comprises a .pi.-allkyl nickel halide supported on an acidic inorganic oxide support. If so desired, the support may have been optionally treated with an alkyl aluminum compound. U.S. Pat. No. 3,592,869 also describes a catalyst which is useful for the oligomerization of olefins. A divalent nickel compound and an alkyl aluminum compound are contacted with an olefinic compound. The resulting mixture is then used to impregnate an inorganic refractory oxide support. Another patent, namely U.S. Pat. No. 3,644,564, describes a catalyst for the oligomerization of ethylene which comprises an organo aluminum-free reaction product of a nickel compound which is an atom of nickel in complex with an olefinically unsaturated compound and a fluorine-containing ligand. The catalysts are typically formed in situ. U.S. Pat. No. 3,679,772 describes a process for reacting monoolefins with diolefins, the catalyst for such a reaction comprising a complex of (1) nickel, (2) a group VA electron donor ligand such as an organophosphine, (3) a nonprotonic Lewis acid and (4) a reducing agent which itself may be a Lewis acid, all of which are composited on an acidic silicabased support.
U.S. Pat. No. 3,697,617 describes an oligomerization process involving the use of a catalyst comprising a complex of nickel with a chloro-containing electron donor ligand such as chlorodiphenylphosphine combined with a nonprotonic Lewis acid which is capable of forming a coordination bond with nickel and a reducing agent capable of reducing nickel acetylacetonate to an oxidation state less than 2. This complex may be composited on a solid support comprising an acidic silica-based material such as silica-alumina. The Lewis acid and the reducing agent may comprise the same compound as, for example, ethyl aluminum sesquichloride. U.S. Pat. No. 3,663,451 describes a catalyst which is obtained by reacting a transition metal halide such as nickel halide with a carrier to give a carrier-metal bond. This product is then reacted with a ligand such as a phosphine or ketone and finally activated by treatment with an aluminum alkyl or chloro alkyl.
U.S. Pat. No. 3,755,490 describes the polymerization of an olefin utilizing a catalyst comprising nickel, a Group VA electron donor ligand, a Lewis acid, and a reducing agent on a solid acidic silica-based support. U.S. Pat. No. 3,954,668 is drawn to an oligomerization catalyst comprising a nickel compound, a chloro-containing electron donor ligand, or a phosphorous compound, a nonprotonic Lewis acid reducing agent which is capable of reducing nickel acetylacetonate to an oxidation state of less than 2 and which is also capable of forming a coordination bond with a nickel. U.S. Pat. No. 3,170,904 speaks to a catalyst which is useful for polymerization comprising a large surface area metal of Groups VIIA or VIII of the Periodic Table, boron trifluoride etherate, an organometallic compound of Groups I, II, III or IV or a halo derivatie ov an organomettallic compound of Groups II, III or IV or a hydride of a metal of Groups I, II or III. The large surface area metal which comprises one component of this catalyst is in metallic form as, for example, Raney nickel. If so desired, the catalyst may be composited on a distomaceous earth carrier. In like manner, U.S. Pat. No. 3,170,906 discloses a catalyst which comprises (A) a carrier-supported nickel or cobalt oxide which has been prepared by impregnating the carrier with the hydroxide, organic acid salt, inorganic acid salt, followed by oxidation in the presence of oxygen or a combination of nitrogen and oxygen; (B) a boron, titanium, zirconium, or vanadium halide; and (C) an alkyl metal or alkyl metal halide. In addition to these patents, British Pat. No. 1,390,530 describes an oligomerization catalyst which has been prepared by thermally pretreating a metal oxide carrier material followed by reacting with a halogen-containing organo-aluminum compound and thereafter in a step-wise fashion, impregnating this product with a divalent nickel or cobalt complex at temperatures ranging from -50.degree. to 150.degree. C.
Several other patents which describe oligomerization or polymerization catalysts which are unsupported in nature or processes include Japanese Patent 5024282 which is drawn to a catalyst containing a Group VII metal and tin chloride or zinc chloride as well as Japanese Patent 4722206 which describes an unsupported catalyst prepared by mixing a nickel compound, an aluminum organic compound and a tin tetrahalide. U.S. Pat. No. 3,155,642 describes an unsupported catalyst prepared from an alklyl tin compound and aluminum chloride in addition to a nickel or cobalt compound for the polymerization of a dienic compound. U.S. Pat. No. 3,155,642 also describes an unsupported catalyst comprising a nickel carboxylate, a halide of a metal of Group IV or V and an organoaluminum compound containing at least one alkoxy radical, said catalyst being used for the polymerization of cis-1,4-polybutadiene. Likewise, U.S. Pat. No. 3,457,321 describes an unsupported catalyst prepared from a complex organic compound of a metal of Group VIII, a reducing agent and a tin tetraalkyl compound. Futhermore, U.S. Pat. Nos. 3,483,268 and 3,505,425 are also drawn to unsupported catalysts, the former showing a catalyst comprising nickel acetyl acetonate, an organonickel compound,a nd an activating agent of an aluminum alkyl alkoxide or aluminum trialkyl while the latter is drawn to a process for preparing this catalyst. British Pat. No. 1,123,474 likewise teaches a process for preparing linear dimers using a catalyst comprising a complex organic compound of a metal of a Group VIII and a tin tetraalkyl compound.
In addition to the above patents, other patents have been noted in which a polymerization reaction is effected in the presence of hydrogen. For example, U.S. Pat. Nos. 4,665,139 and 4,665,140 describe a catalyst which is useful for the production of polyethylene having a relatively narrow range of molecular weights. The catalyst which is employed for this reaction comprises an inorganic oxide having surface hydroxyl groups as a support for a vanadium salt and an aluminum alkyl. The hydrogen which is present in the reaction zone or in the ethylene feed is there for the purpose of controlling the molecular weight of the desired polymer and specifically, the higher the ratio of hydrogen to ethylene, the lower the molecular weight. U.S. Pat. No. 4,414,369 describes a process for the preparation of polyethylene in two stages. The catalyst which is utilized to effect this process comprises a transition metal salt such as titanium and magnesium salts supported on a solid carrier. The process involves feeding ethylene to this first stage of said process and an ethylene/hydrogen feed to the second stage. Again, the hydrogen is present to form relatively low molecular weight polymers in the second stage inasmuch as the polymer which is found in the first stage has a relatively high molecular weight. Thus, the product resulting from the two-stage operation contains a polymer having a relatively wide distribution of molecular weights.
U.S. Pat. No. 3,051,690 describes a process for polymerizing olefins in which a hydrogen is utilized as a molecular weigth control agent. The patentee states that he has found that the molecular weight of the polymeric product which is indicated by the viscosity of the product may be controlled within a desired range by the addition of hydrogen to the polymerization system. However, the catalyst which is employed to effect this polymerization comprises a transition metal compound and particularly metal halides such as titanium tetrachloride. The transition metal compound comprises one component comprises an organometallic compound. However, the two-compound catalyst system is not composited on a solid support.
In U.S. Pat. No. 4,383,939, the catalyst which is utilized for the polymerization reaction is prepared by reacting a refractory oxide support with a halogen containing transition metal such as titanium chloride followed by reaction with an alkyl aluminum compound and a transition metal compound of vanadium. The polymerization of olefins is effected in the presence of hydrogen, the purpose of the hydrogen being to control the melt index and thus inversely control the molecular weight of the desired polymeric product. In U.S. Pat. No. 4,357,448, ethylene is polymerized in two steps under different hydrogen partial pressures. However, the catalytic composite which is used to effect this reaction comprises an organoaluminum compound in combination with a catalytic component which has been obtained by reacting a titanium or vanadium halogen-containing compound with the reaction product obtained by reacting a Grignard reagent with a hydropolysiloxane. Again the hydrogen is present to control the molecular weight by controlling the melt index of the product. In U.S. Pat. No. 4,232,140, a feedstock comprising ethylene or ethylene and propylene mixtures is polymerized in the presence of a catalyst comprising triethylene aluminum and a vanadium compound supported on silica gel. The reaction is effected in the presence of hydrogen which again controls the molecular weight properties of the product.
Other patents which relate to polymerization will include U.S. Pat. No. 3,535,297 which discloses a polymerization of ethylene in the presence of a catalyst comprising chromium composited on silica. Again, the use of hydrogen in the reaction mixture is for the purpose of controlling the melt index of the product. U.S. Pat. No. 4,101,600 relates to the dimerization of ethylene in the presence of a two-component catalyst comprising a mixture of an organotitanium and an organoaluminum compound which is not supported. The patent speaks to the use of hydrogen for the purpose of forming low molecular weight products from the titanium catalyst.
It is to be noted from the discussion of the patents in the preceding portion of this specification that the catalysts are for the main part unsupported when used in dimerization or polymerization reaction and utilizes as the active component for the desired reaction a metal such as that of IVB, VB, or VIB of the Periodic Table. This is in contradistinction to the supported catalyst of the present invention which utilizes, as the active metal component thereof, a metal of the iron group of the Periodic Table and, if so desired, a metal of Group IVA of the Periodic Table.
As will hereinafter be shown in greater detail the oligomerization of olefinic hydrocarbons to provide products which possess a desired configuration with respect to the branching or minimal branching of the resultant chain may be accomplished by treating said olefins in the presence of certain catalytic compositions of matter which have been prepared according to the method subsequently described in greater detail, the reaction being effected in the presence of hydrogen which will enable the catalyst to maintain its activity and stability for a relatively long period of time in the presence of certain impurities or poisons which may be inherently present in the olefinic hydrocarbon feedstock.